In an analog RF (Radio Frequency) circuit, it is important to increase the transconductance (Gm) of a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and to increase the output resistance thereof. In a MOSFET having a general structure, it is sometimes necessary to shorten the length of its gate in order to improve the transconductance (Gm). However, shortening the length of the gate decreases the output resistance. Furthermore, there is also a problem of punch-through (destructive discharge), which is likely to occur when high voltage is applied to the drain and the risk of a short circuit between the drain and source is increased.
A DWF-MOSFET (Dual Work Function Metal-Oxide-Semiconductor Field Effect Transistor, hereinafter referred to as DWF-FET) using gate electrodes having different work functions on the source side and the drain side is a technique capable of improving the transconductance (Gm) without shortening the gate length. However, even in the DWF-FET, a problem remains that the gate resistance is increased depending on the layout of the electrodes.